feat(api-kit): add sonic transaction service url

[0xnook]

What it solves

When initializing safe api key with Sonic chainId 46 without specifying the txServiceUrl

new SafeApiKit({
      chainId: 46n,
      // txServiceUrl: 'https://safe-transaction-sonic.safe.global/api'
})

The error TypeError: There is no transaction service available for chainId 46. Please set the txServiceUrl property to use a custom transaction service. is thrown

How this PR fixes it

By adding the Sonic tx service url to the TRANSACTION_SERVICE_URLS dict

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[0xnook]

I have read the CLA Document and I hereby sign the CLA